CIDR Calculator
Analyze IPv4 CIDR blocks instantly with derived subnet mask, network and broadcast addresses, usable host range, wildcard mask, and host counts. Perfect for route planning, cloud networking, and infrastructure operations.
Complete Guide: CIDR Calculator
Everything you need to know about using this tool effectively
The CIDR Calculator computes network details from a CIDR (Classless Inter-Domain Routing) notation like 192.168.1.0/24. It calculates the network address, broadcast address, subnet mask, wildcard mask, total hosts, and usable host range. All processing happens in the browser.
This tool parses a CIDR notation string (IP address and prefix length), applies bitwise operations to compute the network and broadcast addresses, and derives the subnet mask, wildcard mask, and host count. It handles both IPv4 CIDR notation.
Planning network subnets
Calculate how many hosts fit in a /24, /25, or /26 subnet for network design.
Troubleshooting network issues
Determine if two IP addresses are on the same subnet by comparing their network addresses.
Configuring firewall rules
Calculate the exact IP range for a CIDR block to configure firewall allow/deny rules.
Learning subnetting
Understand how CIDR notation maps to network addresses and host ranges.
Enter CIDR notation
Type an IP address with prefix length (e.g., 192.168.1.0/24).
Calculate
Click Calculate. The tool shows all network details.
Copy results
Copy the network address, subnet mask, or other values you need.
/24 gives 256 addresses (254 usable hosts). /25 gives 128 (126 usable).
/32 is a single host. /31 is a point-to-point link (2 addresses).
The first address in a subnet is the network address. The last is the broadcast address.
Usable hosts = total addresses minus 2 (network and broadcast).
What is CIDR notation?
CIDR notation represents an IP address and its network prefix length, like 192.168.1.0/24. The /24 means the first 24 bits are the network portion.
How many hosts fit in a subnet?
2^(32-prefix) - 2 usable hosts. A /24 has 254 usable hosts. A /28 has 14.
Is my data sent to a server?
No. All calculation happens in your browser. Nothing is transmitted.
What is the difference between network and broadcast addresses?
The network address identifies the subnet (all host bits zero). The broadcast address reaches all hosts on the subnet (all host bits one). Neither can be assigned to a host.
Can I calculate subnet ranges?
Yes. Enter any CIDR block and the tool shows the full range from the first usable host to the last usable host.